S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Computer Science and Engineering (컴퓨터공학부) Theses (Master's Degree_컴퓨터공학부)
Semi-mirror : Performance Improvement of Mirroring for Heterogeneous Storage Environments
- Issue Date
- 서울대학교 대학원
- 학위논문 (석사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2012. 2. 염헌영.
- A Solid State Drive (SSD) is a storage device that has the advantages of high
speed and low power consumption, but that is more expensive than the Hard
Disk Drive (HDD). A recently developed high-performance storage server
combines the features of an SSD and an HDD, containing a large HDD and
a smaller SSD cache to improve system performance of frequently accessed
files. However, existing mirroring techniques such as RAID-1 between an
SSD and a HDD are not suitable for write-intensive workloads because of
the slow HDDs random write performance. Addressing this issue, this paper
presents a new mirroring technique, named semi-mirror, built on top
of Linuxs device mapper architecture. It has three characteristics. First, it
exploits the HDD bandwidth in append-only fashion. Second, it offers the
same availability and reliability as existing mirroring techniques. Lastly, in
the case of power or mechanical failure of the primary device, semi-mirror
offers a recovery process, making a copy from the mirror device (HDD) to
the primary device (SSD). Semi-mirror shows 26 times higher performance
than dm-raid1 in case of random write in IOzone, and it leads to 5-6 times
performance improvement in TPC-C.
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